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A solution of a carbonyl compound is added to a Grignard reagent. (See gallery) An example of a Grignard reaction (R 2 or R 3 could be hydrogen). The Grignard reaction (French:) is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ...
In acidic conditions, alkyl substituents acting as electron withdrawing groups decrease the reaction rate. [10] As bulker silyl groups are more likely to be electron withdrawing, it is easier to differentiate between less and more bulky silyl groups. [10] Therefore, acidic deprotection occurs fastest for less sterically bulky alkyl silyl groups ...
Less frequently silanols are prepared by oxidation of silyl hydrides, a reaction that uses a metal catalyst: 2 R 3 SiH + O 2 → 2 R 3 SiOH. Many silanols have been isolated including (CH 3) 3 SiOH and (C 6 H 5) 3 SiOH. They are about 500x more acidic than the corresponding alcohols. Siloxides are the deprotonated derivatives of silanols: [22 ...
Reactions of Grignard reagents with carbonyls. The most common application of Grignard reagents is the alkylation of aldehydes and ketones, i.e. the Grignard reaction: [16] Reaction of CH 3 C(=O)CH(OCH 3) 2 with H 2 C=CHMgBr. Note that the acetal functional group (a protected carbonyl) does not react.
Trimethylsilylacetylene is commercially available. It may also be prepared in a manner similar to other silyl compounds: deprotonation of acetylene with a Grignard reagent, followed by reaction with trimethylsilyl chloride. [4] Trimethylsilylacetylene is a precursor to 1,4-bis(trimethylsilyl)buta-1,3-diyne, a protected form of 1,3-butadiyne. [5]
Phenylsilane is produced in two steps from Si(OEt) 4.In the first step, phenylmagnesium bromide is added to form Ph−Si(OEt) 3 via a Grignard reaction.Reduction of the resulting Ph−Si(OEt) 3 product with LiAlH 4 affords phenylsilane.
To increase the rate of reaction, trimethylsilyl triflate may also be used in the place of trimethylsilyl chloride as a more electrophilic substrate. [ 4 ] [ 5 ] When using an unsymmetrical enolizable carbonyl compound as a substrate, the choice of reaction conditions can help control whether the kinetic or thermodynamic silyl enol ether is ...
The major advantage of this method over addition of organometallic reagents to more typical acyl compounds is that it avoids the common problem of over-addition. For these latter reactions, two equivalents of the incoming group add to form an alcohol rather than a ketone or aldehyde. This occurs even if the equivalents of nucleophile are ...